This disclosure relates generally to hydrocarbon exploration and production, and in particular to forming well bore tubulars to facilitate hydrocarbon production or downhole fluid injection.
Conventionally, when a wellbore is created, a number of casings are installed in the borehole to prevent collapse of the borehole wall, and to prevent undesired outflow of drilling fluid into the surrounding formation and inflow of fluid from the formation into the borehole. The borehole is drilled in intervals. At each successive lower interval, a casing which is to be installed is lowered through previously installed casings at upper borehole intervals. As a consequence of this procedure, the casing of the lower interval is of smaller diameter than the casings of the upper intervals. Thus, the installed casings are in a nested arrangement with casing diameters decreasing in a downhole direction. Cement annuli are then provided between the outer surfaces of the installed casings and the borehole wall to seal the casings with the borehole wall.
As a consequence of the nested casing arrangement, a relatively large borehole diameter is required at the upper end of the wellbore to achieve the desired flowbore diameter extending downhole into the well. Such a large borehole diameter involves increased costs due to heavy casing handling equipment, large drill bits, and increased volumes of drilling fluid and drill cuttings. Moreover, increased drilling rig time is involved due to required cement pumping, cement hardening, equipment changes due to large variations in hole diameters drilled in the course of the well, and the large volume of cuttings drilled and removed.
The principles of the present disclosure are directed to overcoming one or more of the limitations of the existing systems and processes for increasing hydrocarbon production or fluid injection.